I noticed that even the most basic Winform application (ie. just a window, with no extra modules) still takes several seconds to load after creating its machine code equivalent through Ngen. I guess then that the bottleneck is loading the .Net framework from disk.
Microsoft's CacheSet doesn't allow managing the actual contents of the disk cache.
Is there an application that can force Windows to keep the main .Net files in its disk cache, as a work-around to slower startup time for .Net applications?
Edit: Here's the screenshot of Process Monitor's Process Timeline: